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<title>Debugging with GDB: Trace Files</title>

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<a name="Trace-Files"></a>
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Previous: <a href="Tracepoint-Variables.html#Tracepoint-Variables" accesskey="p" rel="prev">Tracepoint Variables</a>, Up: <a href="Tracepoints.html#Tracepoints" accesskey="u" rel="up">Tracepoints</a> &nbsp; [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Concept-Index.html#Concept-Index" title="Index" rel="index">Index</a>]</p>
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<hr>
<a name="Using-Trace-Files"></a>
<h3 class="section">13.4 Using Trace Files</h3>
<a name="index-trace-files"></a>

<p>In some situations, the target running a trace experiment may no
longer be available; perhaps it crashed, or the hardware was needed
for a different activity.  To handle these cases, you can arrange to
dump the trace data into a file, and later use that file as a source
of trace data, via the <code>target tfile</code> command.
</p>
<dl compact="compact">
<dd>
<a name="index-tsave"></a>
</dd>
<dt><code>tsave [ -r ] <var>filename</var></code></dt>
<dt><code>tsave [-ctf] <var>dirname</var></code></dt>
<dd><p>Save the trace data to <var>filename</var>.  By default, this command
assumes that <var>filename</var> refers to the host filesystem, so if
necessary <small>GDB</small> will copy raw trace data up from the target and
then save it.  If the target supports it, you can also supply the
optional argument <code>-r</code> (&ldquo;remote&rdquo;) to direct the target to save
the data directly into <var>filename</var> in its own filesystem, which may be
more efficient if the trace buffer is very large.  (Note, however, that
<code>target tfile</code> can only read from files accessible to the host.)
By default, this command will save trace frame in tfile format.
You can supply the optional argument <code>-ctf</code> to save date in CTF
format.  The <em>Common Trace Format</em> (CTF) is proposed as a trace format
that can be shared by multiple debugging and tracing tools.  Please go to
&lsquo;<code>http://www.efficios.com/ctf</code>&rsquo; to get more information.
</p>
<a name="index-target-tfile"></a>
<a name="index-tfile"></a>
<a name="index-target-ctf"></a>
<a name="index-ctf"></a>
</dd>
<dt><code>target tfile <var>filename</var></code></dt>
<dt><code>target ctf <var>dirname</var></code></dt>
<dd><p>Use the file named <var>filename</var> or directory named <var>dirname</var> as
a source of trace data.  Commands that examine data work as they do with
a live target, but it is not possible to run any new trace experiments.
<code>tstatus</code> will report the state of the trace run at the moment
the data was saved, as well as the current trace frame you are examining.
Both <var>filename</var> and <var>dirname</var> must be on a filesystem accessible to
the host.
</p>
<div class="smallexample">
<pre class="smallexample">(gdb) target ctf ctf.ctf
(gdb) tfind
Found trace frame 0, tracepoint 2
39            ++a;  /* set tracepoint 1 here */
(gdb) tdump
Data collected at tracepoint 2, trace frame 0:
i = 0
a = 0
b = 1 '\001'
c = {&quot;123&quot;, &quot;456&quot;, &quot;789&quot;, &quot;123&quot;, &quot;456&quot;, &quot;789&quot;}
d = {{{a = 1, b = 2}, {a = 3, b = 4}}, {{a = 5, b = 6}, {a = 7, b = 8}}}
(gdb) p b
$1 = 1
</pre></div>

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